The Power of Copper

So those of you who lurk on my Facebook page undoubtedly noticed my rant the other day, which was in regards to this video:

The video was posted via this link, and it was the website that raised my blood pressure to alarming levels. What set me off was not the content of the website, but the delivery and execution. Well, the content set me off a bit too.  No real need to sit through the full 8+ minutes of it; here is a summary of the video. In the video, a copper surface and a stainless steel surface were coated with Staphylococcus aureus, and mixed with a chemical that glows when excited by fluorescent light AND if the cells are alive. The video then showed microscopic scenes of mass death by the bacteria on the copper surface, but complete survival of the organisms on the steel surface, and the conclusion was that copper somehow has antimicrobial properties.  Let’s see in what ways this set off Prof. Singleton’s Bogosity Meter:

I had some basic problems with the presentation in the video. First, the ultraviolet light source in the microscope is harmful to cells.  Cells are rapidly damaged by the non-ionizing radiation, and will die within the timeframe showed in the video. Now, as set up, they did have a control in the study, which was the steel surface, but we only have the indirect evidence of the video that it was carefully controlled. Second, chemicals which are added to fluoresce under ultraviolet light will quench, or lose their fluorescent intensity, upon continued UV exposure. I’ve used a microscope like that one many times in the past, and a field of microorganisms will lose light intensity like they showed, simply by being exposed to the ultraviolet light. Again, they had the control steel surface, but again we are at the mercy of the camera operator to assess whether it is being done legitimately. Third, many metal ions do have antimicrobial properties, but the copper plate is elemental copper, not ionic copper.  I suspect very little copper is able to dissociate from the surface, and penetrate into the cell.

The website also has a “How it works” section:

Science suggests that copper surfaces affect bacteria in two sequential steps: the first step is a direct interaction between the surface and the bacterial outer membrane, causing the membrane to rupture. The second is related to the holes in the outer membrane, through which the cell loses vital nutrients and water, causing a general weakening of the cell.

After membrane perforation, copper can inhibit any given enzyme that ‘stands in its way’, and stop the cell from transporting or digesting nutrients, from repairing its damaged membrane, from breathing or multiplying.

Based on the press release video and website, I remain incredulous of the claims. Further, some of the proposed mechanism in the above quote also is poor, not the least of which is that S. aureus used in the video doesn’t have an outer membrane because it is Gram positive! Even if the website actually means the plasma membrane, the claim that copper enters the cell to block enzyme function seems unlikely, for the dissociation issue above.

Where does this stand then?  The press release website does list a “Scientific References” section, with peer-reviewed articles from reputable scientific journals. I will be looking particularly closely at this article about the ability of copper to kill yeast. I am hoping that the website summary quoted above is written for the lay-person, and not for someone with a small amount of scientific knowledge, because copper surfaces (if they work) would be a novel way to try and combat the rise of nosocomial infections. We will all reserve final judgement on this until all of the facts are in!

BONUS:  For 100 bonus points, conduct a set of controlled experiments to support or refute the above claims!  Actually, I am kidding about the bonus points, but if anyone would like to learn some more about this,  I would be very interested in working with you on a research project along these lines. You would almost certainly be able to get Independent Study credit for it at YCP, and could use it for any Clinical Research projects you have in your coursework.


About ycpmicro

My name is David Singleton, and I am an Associate Professor of Microbiology at York College of Pennsylvania. My main course is BIO230, a course taken by allied-health students at YCP. Views on this site are my own.

Posted on April 9, 2011, in Bonus!, Microbes in the News, Rant. Bookmark the permalink. 3 Comments.

  1. I agree, I think if copper had actual antimicrobial proporties, it would have been discovered already and it would probably have been in use in some kind of process. Are you sure about those bonus points? I think I would literally do anything for 100 bonus points…

    • Don’t get me wrong! Copper definitely has antimicrobial properties. See for instance, page 275 of our textbook, or this article on Wikipedia. But, as the textbook indicates, it is copper ions that have antimicrobial properties, not metallic copper. I will speak to a chemist to find out how rapidly copper dissociates in this situation.

  2. Copper is actually the first compound used in the control of fungal plant pathogens, with the creation of Bordeaux Mixture in the 1870s by Pierre Alexis Millardet. The copper is applied as copper sulfate, with the copper being is a +2 oxidation state. The copper prevents spore germination, so when applied in advance prevents disease.

    Source: Agrios, G. 2005. Plant Pathology. 5th Ed. Elsevier Academic Press, Amsterdam.

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